Chapter 8 Multiplexing Many to oneone to many

Multiplexing Frequency -Division Multiplexing (FDM) Time-Division Multiplexing(TDM) Synchronous Asynchronous

Synchronous TDM • Allocates exactly the same time slot to each device at all

Data Rate Bit Stuffing: Add extra bits to a stream of data such that

Frames and Addresses a. Only three lines sending data

Frames and Addresses • Asynchronous TDM supports the same number of input lines with

Frames and Addresses c. All five lines sending data

services Analog services Digital services

Why Digital? • Less sensitive to noise. • Inexpensive. • Better quality.

Switched/56 Service Digital Service Unit (DSU): Changes the data rate to 56 Kbps and

Digital Data Service (DDS) • The digital version of the analog leased line. •

T Lines • DS-1, DS-2, … are services, T lines are the lines for

E Lines • European version of T lines. Line Rate (Mbps) Voice Channels E-1

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Chapter 8 Multiplexing • Many to one/one to many • Types of multiplexing • Telephone system

Multiplexing vs. No Multiplexing

Multiplexing Frequency -Division Multiplexing (FDM) Time-Division Multiplexing(TDM) Synchronous Asynchronous

FDM

FDM, Time Domain

Multiplexing, Frequency Domain

Demultiplexing, Time Domain

Demultiplexing, Frequency Domain

TDM

Synchronous TDM • Allocates exactly the same time slot to each device at all times, whether or not a device has anything to transmit.

TDM, Multiplexing

TDM, Demultiplexing

Framing Bits

Data Rate Bit Stuffing: Add extra bits to a stream of data such that the devices data rates are integer multiple of each other.

Asynchronous TDM (Statistical TDM)

Frames and Addresses a. Only three lines sending data

Frames and Addresses • Asynchronous TDM supports the same number of input lines with a lower capacity link. • The total speed of the input lines can exceed the capacity of the path.

b. Only four lines sending data

Frames and Addresses c. All five lines sending data

Multiplexing and Inverse Multiplexing

Telephone Network

services Analog services Digital services

Analog services Switched Leased

Analog Switched Service )PSTN

Analog Leased Service

Analog Hierarchy

Digital services Switched/56 DDS DS

Why Digital? • Less sensitive to noise. • Inexpensive. • Better quality.

Switched/56 Service Digital Service Unit (DSU): Changes the data rate to 56 Kbps and encodes it into the format used by the service provider. Support bandwidth on demand.

Digital Data Service (DDS) • The digital version of the analog leased line. • Subscriber can choose among 5 data rates: 2. 4, 4. 8, 9. 6, 19. 2, or 56 Kbps.

Digital Signal Service (DS) Hierarchy`

T Lines • DS-1, DS-2, … are services, T lines are the lines for transmission digital data, voice, etc. Service Line Rate (Mbps) Voice Channels DS-1 T-1 1. 544 24 DS-2 T-2 6. 312 96 DS-3 T-3 44. 736 672 DS-4 T-4 274. 176 4032

T-1 Line

T-1 Frame

Fractional T-1 Line

E Lines • European version of T lines. Line Rate (Mbps) Voice Channels E-1 2. 048 30 E-2 8. 448 120 E-3 34. 368 480 E-4 139. 264 1920